Corner Capacitance of Narrow Strip in Rectangular Cross Section Envelope

The 2D capacitance of a thin (zero thickness) strip in the center of rectangular cross section envelope can be evaluated using the formulas for 2D "corner" geometric capacitances or permeances. If the width of the strip is larger than the height of the envelope the known corner capacitance for infinitely wide strip can be used, In the paper, using conformal mapping with special functions and numerical conformal mapping, more exact approximate formulas than existing. are proposed for the case of narrow strip, with the width smaller than envelope height.